1. Field of the Invention
The present invention relates to drill bit engines, and more specifically, to drill bits and drill bit engines having particular utility in drilling through a variety of materials.
2. Prior Art
The need for drill bits to drill through a wide variety of rocks is well known in the art. This problem is compounded by the fact that, for example, in the drilling of a typical oil well, different types of earth formations are encountered as the drill extends into the earth's surface. While the first layer of earth mostly may be relatively easy to penetrate, the additional layers may present conditions where the drill bit will no longer properly function. Of course, even when drilling a hole in a relatively homogeneous type of material, large rock formations can also be encountered which will break the drill bit or otherwise prevent the drill bit from penetrating therethrough. This has led the prior art to design the wide variety of drill bits which use various types and shapes of drilling heads. The most common of these are drilling heads including a plurality of outwardly extending tooth-like members disposed on the bottom of the bit which tooth-like members rotate in varying directions. Upon engagement of the earth's surface, the members "eat" their way through the earth and thus form the well hole. However, the problems associated with such a drill bit are many. One of the most critical is that while such teeth can go through certain types of rock, the speed at which they go through hard rock is extremely slow which tends to wear the teeth down. This has necessitated the replacement of such drilling heads many times before such rock is finally penetrated.
As the need for exploration of natural resources increases, the need to find a better system for drilling in a wide range of environments has also increased. One recent development has been the use of liquid fuels and an associated jet nozzle to produce a high temperature flame. The flame is used as the cutting means by which the drill proceeds through the ground. An example of such type of drill bit is disclosed by Elmore, U.S. Pat. No. 3,620,313. In the Elmore device, a liquid propellant is burned in bulk mode to produce high combustion pressures with a relatively large power output. Such energy density produced by the buring of the liquid propellant enable the device to drill relatively deep holes. In the use of such a device, the fuels used have been hydrazine, diesel fuel, nitric acid and the like. While such flame drills have been found to be particularly useful in drilling a wide variety of rocks, the rate at which these type of drills have proceeded through the earth's surface has not been as rapid as initially anticipated. It has been determined that the problem encountered by such a drill bit is that the surface adjacent the nozzle of the flame tends to melt and cool the rock before it is carried away. This melted rock formation has a thermal conductivity range which is many times broader than the initial rock formation. In other words, the melting action of the rock produces a barrier adjacent the drill bit nozzle which decreases the rate at which the nozzle can proceed.
Other prior art device is disclosed by Fleming, U.S. Pat. No. 3,045,766. In the Fleming device, a burner is disposed adjacent the bottom thereof and is used as a means for penetrating the ground. The Fleming device also includes a cooling system in which cooling waters flow through various passages adjacent the burner and discharge adjacent the burner tip in a generally upward direction. Because of the heat associated with the flame jet, the water is converted into steam which contacts the rock. The cooling water and the steam thus produced is described as being the medium for carrying the cuttings out of the hole. Moreover, as discussed with the other prior art, Fleming makes no reference to the use of an additional jet as a means for increasing the rate at which the drill bit can be used to penetrate the rock formation.
The present invention represents an advancement in the art of rock piercing means and contains none of the aforementioned shortcomings associated with the prior art devices. The present invention thus provides an apparatus which can be used for a wide variety of rock formations and which uses a combination of water jet piercing and flame jet piercing techniques. By the use of this combination, unexpected speed through various types of rocks is achieved.